Is this arching wrong ?

[Anders Buen]

2 hours ago, reguz said:

Anders, The equipement is in a closed room made of concrete wall roof and floor on a marble table. The temperature is constant the humidity is constant. A camera make pictures that become handled in a computer.. Yes the red light is the only light. All this is done by experiented people at the LTH university. I do not know what the system is called. We did this 2007

Ok, there are two gorups in scandinavia on this type of instrumentation, thoe one I attended in NTH now NTNU, mainly Ole Johan Løkberg in Trondheim. And the group around Nils Erik Molin at Luleå. Molin worked with a doublpulsed laser as well, just like the NTNU Optics lab. They had a 1W continuous Argon laser (green light) the water cooled huge system almost 2m long resonator, I had access to for a while and they worked with a double pulsed one, or just a pulsed one, Co2 (?) laser infrared for high speed work, like bursting airbubbles for the oil industry, seismic bubble bursts in a water tank.

Molin do not live any longer, he passed in late 2022, but they pioneered monitoring the development of a vibration shape from an impact. I think they use an airdriven 4,5mm gun for the puspose. E.g they pictured violin wooden blanks of spruce and maple, a ruler and flat plates of different types with the double pulsed laser.

All these also, most likely, worked on military related projects servicing officiel reseach organsisations on their projects. However, they do have a series of violin and instrument related measurements and publications, some of which are «classic» although not all that useful. Molin more than Løkberg, because of Erik V Jansson and KTH´s speech and music group and research.

I am interested in the RH related properties of insturments and the mechanisms and have done some experiments as well as written about it. Also related to CLT (cross laminated timber in buildings). I have a draft for a paper written around 2010 on this, but did not finish it after the constructive revievs came. The editor told me to merge two articles I had on it, and  one of the revievers told me to separate them again :-) All the article drafts and a power point is shared on Researchgate.

I have loggers going in two buildings here in Olso over several years now, in oder to find the natural variation outside, inside, in the shelf for fiddles and in the case. Alo looking for the «transient times». 

NTNUs system was called RETRA 1000. And we had a really good amplifier with a signal generator with a sensitive steering ewheel and resolution. I do think Molin had a commercialised optics version too. His last article was on laser optics interferometry use in vibration monitoring in a springer book chapter. Molin could technically have been at that lab in 2007.

   

Edited December 14, 2023 by Anders Buen
Additional info

[HoGo]

3 hours ago, reguz said:

To answer your description briefly. I ask the question; have you applied what you describe and can you explain your results understandable for us violin makers who don't have math skills

?????

You presented yourself as engineer or something like that and you "school" swedish university/PhD students working on their theses but you don't understand such ELEMENTARY thing as coordinate system? We teach that on high school Math classes. All including vector spaces etc. Every university engineering course I know starts with that and lots of other applied maths and physics.

Now you present yourself as violin maker but no one has ever seen a violin made by you. There's not even mention of one enywhere on interned except some of your somewhat unclear suggestions.

[Peter K-G]

On 12/13/2023 at 12:14 PM, reguz said:

In a workshop in Cremona attending of 17 makers at Toto's place we checked the locations of the STL on their plates. Only one had exactly location compared with the geometric model. How was that possible? Well Toto came with a caster plast of a Stradivari instrument. He had made the "six" for shaping the arching and came out with the STLs as they are on the geometric model. We became very surprised. How could this be?

It is an experience learning that STLs are on the Strad caster plast as I found them by geometric constructing.

It could be possible that Strad gave his workers the templates to work and shape after. Well done Strad checked the result of the STLs and probably made some corrections.

What however is important is that also on the inside there must be made STL shape at the same location. First in that state we have a "beam" that make part of the octrahedrone Framework.

This was tested in the master dissertation and found that the straight STL condition remain. So, it is given proof that the framework function and thus the behavior of the bout shapes that become deflected. 

Having this result, we may start thinking of how graduating the thickness in relation to that shape and the wood quality. The result comes from experimenting

 

On 12/13/2023 at 6:39 PM, Peter K-G said:

There could be a much simpler explenation.

Once you realize how to make them look in a certain way, which is developing knowledge of a visual 3D shape, that is linked to the plate outline and in combination with working metod, will automatically give STL:s like you describe.

And it is no coincident that this shape would be a good structure that can be found by engineering a model.

 

On 12/13/2023 at 10:26 PM, reguz said:

In the begining I searched for special conditions as I described and well found I liked to find if the geometry also produce STL condition which it does. Yes STL on arching shape arises on many diffrent location depending how you shape your arching, This we looked at in the workshop of TOTO as decribed earlier

Look at page 2, that's how STL:s are on my violins. And they come out this way naturally as a consequence of working method.

https://andrewryanviolins.godaddysites.com/publications

[LCF]

11 hours ago, Delabo said:

If the sound post is not a stable reference point, then what part of a violin can be used as a datum, if any?

Player's chin. 

[LCF]

10 hours ago, Delabo said:

Oops, I should have said "datum point", hope thats better?

Isn't datum already the singular of data?

[reguz]

11 hours ago, Peter K-G said:

 

 

Look at page 2, that's how STL:s are on my violins. And they come out this way naturally as a consequence of working method.

https://andrewryanviolins.godaddysites.com/publications

Peter it might very well be that people observed the transition from convex to concave on their arching shape. However, now one thought about that the STLs on belly and back produce a framework like an octahedron. With a sound post between the two a very stable structure arises. I claim the sound post thus the center of the instrument cannot become forced down as shown by GOLI, GOUGH, CURTIN, STOPPANI, SCHLESKE.

the result of what they do might be correct by their calculations and handling the object as they do but this do not happen on the structure by string load. The only possible way observing correct is by holding the instrument 90 degree rotated so gravitation NOT involve what happens. When you hold the instrument under your chin completely different conditions arises. I have not studied such condition. I am only interested in what string load do with the structure and one must not include condition like gravitation.

What happens in the playing condition no one ever can give a good answer on!! Every instrument behave different.

[reguz]

12 hours ago, HoGo said:

?????

You presented yourself as engineer or something like that and you "school" swedish university/PhD students working on their theses but you don't understand such ELEMENTARY thing as coordinate system? We teach that on high school Math classes. All including vector spaces etc. Every university engineering course I know starts with that and lots of other applied maths and physics.

Now you present yourself as violin maker but no one has ever seen a violin made by you. There's not even mention of one enywhere on interned except some of your somewhat unclear suggestions.

HUGO. it is all about thinking how early violin makers can understand. If you with your wisdom can do better and learn us JUST DO IT. Most people making instrument do not understand what you are talking about

[reguz]

12 hours ago, HoGo said:

?????

You presented yourself as engineer or something like that and you "school" swedish university/PhD students working on their theses but you don't understand such ELEMENTARY thing as coordinate system? We teach that on high school Math classes. All including vector spaces etc. Every university engineering course I know starts with that and lots of other applied maths and physics.

Now you present yourself as violin maker but no one has ever seen a violin made by you. There's not even mention of one enywhere on interned except some of your somewhat unclear suggestions.

if you see some picture, are you satisfied? Is this the problem for you?

[Peter K-G]

1 hour ago, reguz said:

Peter it might very well be that people observed the transition from convex to concave on their arching shape. However, now one thought about that the STLs on belly and back produce a framework like an octahedron. With a sound post between the two a very stable structure arises. I claim the sound post thus the center of the instrument cannot become forced down as shown by GOLI, GOUGH, CURTIN, STOPPANI, SCHLESKE.

the result of what they do might be correct by their calculations and handling the object as they do but this do not happen on the structure by string load. The only possible way observing correct is by holding the instrument 90 degree rotated so gravitation NOT involve what happens. When you hold the instrument under your chin completely different conditions arises. I have not studied such condition. I am only interested in what string load do with the structure and one must not include condition like gravitation.

What happens in the playing condition no one ever can give a good answer on!! Every instrument behave different.

Why is this still an issue? It has been countered many times, that it depends on the viewpoint. Please explain as clear as possible what you mean. There has been thousands of post back and forth on this and it's not going to end before you explain clear and simple.

The other explanation would be that you have some disorder and can't look at things from different views. But I still believe you are sane.

Please don't post the same images and texts over again. Maybe you can continue with my question earlier

 

Is This what you want to discuss?

 

 

[fscotte]

On 12/11/2023 at 7:57 AM, Andreas Preuss said:

Not quite. There are quite many Cremonese instruments which suffer from a sunken-in top plate. (Or pulled up end blocks, depending how you see it.)

If you can feel it vibrate, then it's moving.

Does that pretty much summarize what this entire thread is about?

[Dr. Mark]

1 hour ago, fscotte said:

If you can feel it vibrate, then it's moving.

Spoilsport

[David Burgess]

On 12/15/2023 at 4:52 AM, reguz said:

However, no one thought about that the STLs on belly and back produce a framework like an octahedron.

Of course people have! The issue is that the load-bearing area of these STLs is so small, and is cross-grain enough, that its structural significance is negligible.

[LCF]

There seems to be an assumption in this theory that the two sides of the top would respond equally to the static string tension. But of course the presence of bass bar mandates that any possible 'ideal' arching pattern  should differ from one side to the other because the stresses have a different pattern thus the deflections will be different. 

Forget about theoretical models. From direct photographic observation and from the  knowledge of experts we see that no matter where an instrument is held or thrown,  in photos of classic instruments taken in side view one frequently sees a bending up of the whole instrument referenced along the edge of the top plate, one bump up in the centre of the upper bout and one in the lower bout and a dip around the bridge area matched by a bulging out of the back under the soundpost.

It is a falsehood to make a direct connection between the response of the violin body to static string loading forces and torques in a lengthways direction as opposed to the way that oscillating forces are applied to the soundboard via the bridge  --- these are a very complex combination of downwards forces and crossways torques. 

The observations of Andreas Preuss, that rib stiffness is a hugely significant factor in tonal outcomes underlines how relatively unimportant this theory of stl  is. 

 

Let's move on. 

[Marty Kasprzyk]

 

I totally eliminate the buckling causing longitudinal string force on the top plate by attaching the strings to an extension of the fingerboard rather than the usual endpin.

The downward string force on the top plate at the bridge is reduced by about a half by using a shallow 170 degree string angle over the bridge instead of the usual 158 degree angle.

This string downward force on the top is further halved by using only the bass side bridge foot resting on the top plate. The treble foot rests directly on the sound post which goes through to top plate. So the total downward string force on the top plate is only about 1/4 the normal amount.

These two things allow the top plate to be made thin, light and flat and its low mass and stiffness increases the sound output.  This in turn allows lighter tension strings to be used which further reduces the loading and also makes the instrument respond quicker to bowing.

 

 

[Dr. Mark]

[Mr. Kasprzyk]

Frankly I admire your work and the direction you've taken.  I'd jump right in if I was less paranoid, and ergo conservative with regards to where I expend my time and energy.  So a question from this conservative perspective: is the general consensus that your creations have the tone and projection that's accepted by, or better, desired by professional players of the standard repertoire?  Another related question: do they sell, i.e. have you established a reasonably robust market for your instruments (or do you care lol)?

[reguz]

6 hours ago, fscotte said:

If you can feel it vibrate, then it's moving.

Does that pretty much summarize what this entire thread is about?

 

3 hours ago, David Burgess said:

Of course people have! The issue is that the load-bearing area of these STLs is so small, and is cross-grain enough, that its structural significance is negligible.

 

3 hours ago, David Burgess said:

Of course people have! The issue is that the load-bearing area of these STLs is so small, and is cross-grain enough, that its structural significance is negligible.

David, something become a structural member when we give it in the case of the STL a thickness. With other words there is an STL on the inside shape of arching. On one side it is growing convex while on the other side growing concave. It is just this special structural behavior that it make strucure rotating on the STL structure. So forces comming from the end block direction buckel the bout hspae that rotate and force down the other side. That make the C-bout beoming wider. So there arises in the dynamic state an alternating structural delection that make the instrument shorter and wider.

 

5 minutes ago, Dr. Mark said:

[Mr. Kasprzyk]

Frankly I admire your work and the direction you've taken.  I'd jump right in if I was less paranoid, and ergo conservative with regards to where I expend my time and energy.  So a question from this conservative perspective: is the general consensus that your creations have the tone and projection that's accepted by, or better, desired by professional players of the standard repertoire?  Another related question: do they sell, i.e. have you established a reasonably robust market for your instruments (or do you care lol)?

Dr. Mark I am not a violin maker although I made quite a number of violins and viola. But all are made for finding proof on what the structure produces.  All with 0,1 mm presession on arching shape with a by me constructed CNC routing equipment. That is the reason why you may read on my site Violin Structure and function. I once became interested in the function of the instrument. What I found show a solution based on simple geometry with lots of answer on 2D layout 3D shape and internal structural qualities. For that reason, i felt I had to make some instruments getting an answer if I am on the right track. I worked together with professional player and twice I worked with the Lund technical University. Holography and a Master degree (not me) that gave me proof that my assumptions are correct. The STL framework is stable and since it holds that function, we are able making the plates thinner without the risk that the collapse. In fact, we can improve on the playable instrument. Much has been on the table "WHAT DID STRAD" becoming able making thinner plates we do not today. Did he treat the wood or is it varnish. I say No it’s the structural shape of arching. Today quite a number of makers make perfect STL frame work and make their best instruments. So, it is with that background I liked to inform you all that I have find out. But GREAT Scientist show for me a contradiction in behavior it is not easy to convince you. I am sure about that I am correct. Their observations have become wrong since they involve Gravitation and support on moving structure when they make their observations. It is simple as that. You cannot force down the center of an octahedron with an inside column. That The Lund Technical University have given proof on and I believe the professors know what they do and accept from the boys that did their masters.

I believe there once was a great intellectual person how could see all what I show now.

[Dr. Mark]

7 hours ago, LCF said:

Forget about theoretical models.

There are two general parts to physical science in my view: observation and book-keeping.  Theory is a form of the book-keeping part and it's intent is to allow us to take things we can measure to predict and rationalize the behavior of a system that depends on these observables.  If that could be done with a violin, then there would be a series of constraints (e.g. wood must have these characteristics (x,y,z) in the following ranges of values: x = [*], y = [*], z = [*]), and rules (e.g. if x, y, and z are within these constraints, then the f-hole edge length should be f(x,y,z) = mumble mumble) & etc. that produce a Strad-quality violin, perhaps with some probability.

An amusing pastime if your wallet and time allows.  Plus, a theoretical solution certainly exists.  There's just comparatively little interest in such a thing so research money is rather limited.  It's left to a few odd graduate students, violin makers with time on their hands (haha), diletantes and various dissatisfied curmudgeons, with an occasional geezer thrown in.  I think that with program funding of $3-4B say from the DoD and spread out over a decade or so, bringing DARPA on-board and using our established community of government contractors, we could make some serious progress.  Or end up like Hanford.  It could end up like Hanford...(insider joke)

[Dr. Mark]

16 minutes ago, reguz said:

Dr. Mark I am not a violin maker although I made quite a number of violins and viola.

Hi - thanks for your response, but my post that you quote was referring to Mr. Kasprzyk's body of work.

[David Burgess]

Reguz, are you familiar with the terms "scotoma", and also "intellectual scotoma"?

[Don Noon]

4 hours ago, LCF said:

Let's move on. 

That would be nice, but the best we can hope for is for this thread, to die out until the next time this exact same topic and arguments get brought up again.

[Sapiens]

Before it dies out, anyone up to sum it up in a few words?

[David Burgess]

31 minutes ago, Sapiens said:

Before it dies out, anyone up to sum it up in a few words?

I could, but it should probably be left to someone more euphemistic and tactfully delicate than I.

[LCF]

1 hour ago, Dr. Mark said:

There are two general parts to physical science in my view: observation and book-keeping.  Theory is a form of the book-keeping part ....

....  Plus, a theoretical solution certainly exists.  There's just comparatively little interest in such a thing so research money is rather limited. 

 

 

When I say 'forget about the theoretical models" it is of course only a short-term plea to look at photos and listen to the conclusions  of skilled observers.

The besr we can hope for regarding the violin research industry is that it suddenly becomes important for defense purposes and attracts billions of dollars in funding. 

[uncle duke]

On 11/30/2023 at 11:20 AM, Nick Allen said:

There really is no wrong arching. There is suboptimal arching for a given piece of wood, but even then the end results are still up to interpretation. 

That is what Mr. Burgess has mentioned in the past.

is there a way to self diagnose for Down’s syndrome or autism?  I think I have both.  Maybe change my diet.

[LCF]

2 hours ago, Don Noon said:

That would be nice, but the best we can hope for is for this thread, to die out until the next time this exact same topic and arguments get brought up again.

There are so many interesting snippets here from diverse participants, it's like fruit on brambles. Enjoy the berries but wear gloves when you're picking them.